Centennial-scale compound-specific hydrogen isotope record of

GEOPHYSICAL RESEARCH LETTERS, VOL. 34, L19706, doi:10.1029/2007GL030303, 2007
Centennial-scale compound-specific hydrogen isotope record of
Pleistocene–Holocene climate transition from southern New England
Juzhi Hou,1 Yongsong Huang,1 W. Wyatt Oswald,2 David R. Foster,2 and Bryan Shuman3
Received 6 April 2007; revised 8 August 2007; accepted 5 September 2007; published 9 October 2007.
[1 ] Northeastern North America experienced major
climate shifts during the Pleistocene – Holocene transition.
However, there have been no high-resolution isotopic
records of climate change from this region. Here, we
present a centennial-scale record of climate change during
the transition based on D/H ratios of behenic acid (C22 nacid) or dDBA from a sediment core in Blood Pond,
Massachusetts. Surface calibrations from a transect of
19 lakes in eastern North America show that dDBA values
track mean annual atmospheric temperature variations. The
abrupt climate events observed in Blood Pond records show
remarkable similarity with Greenland ice core d18O records
during the Pleistocene. During the early Holocene, the
northeastern North America dDBA record was more variable
than Greenland, possibly due to the close proximity of the
Laurentide ice sheet, and impact of freshwater outbursts as
the ice sheet rapidly retreated. Citation: Hou, J., Y. Huang,
W. W. Oswald, D. R. Foster, and B. Shuman (2007), Centennialscale compound-specific hydrogen isotope record of Pleistocene –
Holocene climate transition from southern New England,
Geophys. Res. Lett., 34, L19706, doi:10.1029/2007GL030303.
1. Introduction
[2] The Pleistocene –Holocene transition is characterized
by abrupt climatic fluctuations around North Atlantic Ocean
[e.g., Stuiver et al., 1995; Hughen et al., 1996]. However,
the spatial variations in the timing, amplitude, and phasing
of the abrupt events are less understood on the adjacent
continents. This is particularly true for the northeastern
North America where the driving forces for climate
were particularly complex, comprising a combination of
changes in North Atlantic sea surface temperature, Laurentide ice sheet (LIS) extent, atmospheric composition, and
insolation [e.g., Webb et al., 1993]. Centennial-scale quantitative records from the northeastern North America are
thus extremely important for better understanding marineterrestrial-atmosphere-cryosphere connections and regional
climatic responses.
[3] Existing paleoclimate records from the northeastern
North America are mainly based on paleoecological
approaches, such as assemblages of pollen [e.g., Peteet et
al., 1990; Webb et al., 1993; Shuman et al., 2002] and
Chironomidae (midge) [e.g., Cwynar and Spear, 2001;
1
Department of Geological Sciences, Brown University, Providence,
Rhode Island, USA.
2
Harvard Forest, Harvard University, Petersham, Massachusetts, USA.
3
Department of Geography, University of Minnesota, Minneapolis,
Minnesota, USA.
Walker et al., 1997] from lake sediments. However, the
possibility of transient vegetation responses to short-term,
small-magnitude climate variations [e.g., Davis and Botkin,
1985], and the non-analogue conditions for Chironomidae
[e.g., Kurek et al., 2004] could increase the difficulty of
using pollen and Chironomidae data to assess abrupt
(<centennial-scale) climate variability.
[4] Compound-specific hydrogen isotope analyses of
aquatic lipids in sediments [e.g., Sauer et al., 2001; Huang
et al., 2002, 2004; Dawson et al., 2004] offer a new way to
quantify past climate variations. The technique is especially
useful for regions like northeastern North America where
the lake sediments lack carbonate deposit. Organic compounds produced by algae and macrophytes track lake water
isotopic variations [e.g., Huang et al., 2002, 2004; Hou et
al., 2006; Sauer et al., 2001], which in regions of high
precipitation-evaporation (P-E) ratio, mimic precipitation
isotopic variations. For example, the low resolution record
of D/H ratios of behenic acid (C22 n-acid) or dDBA tracks
general climate variation for the past 16,000 yr at BloodPond [Hou et al., 2006]. The objectives of this study are:
(1) to establish a transfer function between dDBA and surface
air temperature; (2) to quantify the temperature variations of
the abrupt climate events during the Pleistocene – Holocene
transition; and (3) to integrate with other isotopic records
and pollen data to probe the mechanisms of abrupt climate
events in northeastern North America.
2. Samples and Methods
[5] Blood Pond (42.081°N, 71.961°W, 212.1 m above sea
level) is a kettle pond located in Massachusetts (Figure 1).
The lake is mainly recharged by ground water and precipitation, with a southerly overflow outlet. The sediment core
was collected in 2001, and samples for isotope analyses
were selected at 6 cm intervals. Chronology for the core is
provided by AMS-14C dating of bulk organic matter which
were converted to calendar years before present (cal yr B.P.)
using OxCal 3.9 [Hou et al., 2006]. The preparation of
the samples and the measurement of hydrogen isotopes
have been described previously [Hou et al., 2006]. Briefly,
lipids were extracted from freeze-dried sediment using an
Accelerated Solvent Extractor 200 (Dionex). Acid fractions
were isolated, methylated, and purified. A HP 6890 GC
interfaced to a Finnigan Delta+ XL stable isotope spectrometer through a high-temperature pyrolysis reactor was used
for hydrogen isotopic analysis. The precession (1s) of
triplicate analyses was <±2%. The accuracy was routinely
checked by measuring laboratory isotopic standards every
six measurements. Temperature changes of precipitation
were also reconstructed based on pollen assemblages in
Copyright 2007 by the American Geophysical Union.
0094-8276/07/2007GL030303$05.00
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or
0:8681ð1000 þ dDP Þ ¼ 1000 þ dDBA
ð4Þ
Substituting (1) and (2) into (4), we obtain 4.5 (±0.2) T +
770 4.3 (±0.2) T + 792. This suggests that the
relationship between dDBA and T is consistent with that
between dDP and T, when the D/H fractionation during the
biosynthesis of behenic acid is taken into consideration.
Figure 1. Map showing the location of Blood Pond (star),
the GNIP stations (circles), and lakes along north – south
transect (solid triangles).
the same sediment core using the modern analog technique
described by Webb et al. [2003].
3. Results and Discussions
3.1. Relationship Between dDBA and Surface Air
Temperature
[6] D/H ratios of C22 n-acid (dDBA) from lake surface
sediment track lake water D/H ratios along lake transects in
eastern North America [Hou et al., 2006]. However, the
relationship between the dDBA values and surface air
temperature (T) has not been established. Here, we establish
the relationship between dDBA and T along the N – S
transect (Figure 1; see Huang et al. [2004] for details of
the transect) across a temperature gradient (2 to 23°C) in
eastern North America (Figure 2, left),
dDBA ¼ 4:3T 208:4; R2 ¼ 0:96; p < 0:001
ð1Þ
[7] Based on this relationship, a 1°C change in T corresponds to 4.3 ± 0.2% variation in dDBA. To validate this
relationship, we determined the relationship between T and
precipitation dD value (dDP) using the data from Global
Network of Isotopes in Precipitation (GNIP) stations in
eastern North America (Figure 1) [Rozanski et al., 1993].
The dDP data show a linear correlation with T (Figure 2,
right),
dDP ¼ 5:2T 113:0; R2 ¼ 0:97; p < 0:001
ð2Þ
This suggests that 1°C change in T corresponds to a change
of 5.2 ± 0.2% in dDP. The apparent isotopic fractionation
(a) for C22 n-acid relative to lake water is constant along the
transect [Hou et al., 2006]:
a ¼ 0:8681 ¼
1000 þ dDBA
1000 þ dDP
3.2. dDBA Fluctuations and Climatic Implications
[8] dDBA values from Blood Pond sediments show pronounced variations during the Pleistocene– Holocene transition (Figure 3, also see auxiliary material).1 D/H ratios
increased by 20% between 16 and 14.8 ka. The Bølling
and Allerød warm periods were indicated by higher dD
values at 14.8 – 14.4 ka and 14.2 – 13.7 ka, which were
separated by one sample with low dDBA value. The most
significant dD variations were observed at the beginning
and the end of Younger Dryas chronozone (YD). YD was
indicated by lower dDBA values with some fluctuations. The
lowest dDBA value occurred around 12.3 ka. The dDBA
records show similar fluctuations with d 18O records from
GISP2 ice core and Crawford Lake during late Pleistocene
(Figure 3). During early Holocene, dD values showed more
frequent fluctuations with smaller amplitudes, occurred at
10.9, 10.6, 10.3 to 10.1, 9.7, 9.3 and 8.9 ka, respectively.
Although dDBA values in the transect show strong correlation with T (Figure 2, left), dDBA variations with small
magnitude (<10%) and defined by a single sample could be
attributed to other factors in addition to temperature, such as
P-E ratios, hydrological balance of lake water, seasonal
shifts in precipitation. We will focus on major downcore
dDBA shifts to avoid over-interpreting the data as temperature changes.
3.2.1. Late Pleistocene (16 – 13.2 ka)
[9] Surface air temperature increased by 5°C between
16 and 14.8 ka. The warmest period of the Late Pleistocene
occurred between 14.8 and 14.4 ka, coinciding with the
Bølling period (B). The Allerød period (A) is about 2°C
cooler than Bølling. Warmth during the B-A periods inferred from the dDBA data matches the warming pattern
found in Greenland. Three short cold periods defined by
single samples show similar temperature amplitude as those
from GISP2 d 18O (Oldest Dryas, Older Dryas, and Intra
Allerød cold period (IACP), Figure 3), although variation in
P/E ratios and seasonal changes in precipitation may affect
the dDBA changes. The onset of the Bølling period, and the
step-change during B-A periods at Blood Pond appear to
lead the GISP2 temperature changes by about 100 to
300 years. This may not reflect a real difference in phasing,
as the chronological inaccuracies in Blood Pond records
(100– 350 year uncertainties, Figure 3) and/or the reservoir
effect in Blood Pond could readily lead to observed chronological differences.
3.2.2. Younger Dryas Chronozone (13.2– 11.6 ka)
[10] The most significant temperature shifts in the record
occurred at the beginning and end of the YD. The beginning
of YD (13.2 – 13 ka) is marked by 5.6°C decline in
temperature. Temperatures fluctuated during the YD, with
ð3Þ
Auxiliary materials are available at ftp://ftp.agu.org/apend/gl/
2007gl030303.
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Figure 2. Correlation between (left) D/H ratios of behenic acid (C22 n-acid) or dDBA and surface air temperature (T) along
the north – south transect in eastern North America, and (right) mean annual dD of precipitation (dDP) and surface air
temperature (T) for GNIP stations in eastern North America (1961 – 1987, data from Rozanski et al. [1993]).
the lowest temperature occurring at 12.3 ka. The YD
ended abruptly at 11.6 ka, 5.4°C increase in less than
200 years. The dDBA-inferred temperature variations from
Blood Pond can be compared with carbonate d 18O variation
from Crawford Lake in Ontario [Yu and Eicher, 1998]
(Figure 3), White Lake in New Jersey [Yu, 2006], and with
opal d18O change from Linsley Lake in Connecticut
[Shemesh and Peteet, 1998]. The d 18O-inferred temperature
variation in Crawford Lake and White Lake was 6 and
8°C [Yu and Eicher, 1998; Yu, 2006]. The opal d 18Oinferred temperature change in Connecticut was 6°C
[Shemesh and Peteet, 1998]. Temperature changes during
the YD have also been estimated using Chironomidae
assemblages from lakes in the White Mountains of New
Hampshire [Cwynar and Spear, 2001] and from pollen data
in New England [e.g., Huang et al., 2002] and New York
Figure 3. dDBA record and pollen-inferred temperature from Blood Pond during the transition from late Pleistocene to
Holocene in comparison with d 18O data from Greenland Ice Sheet Project 2 (GISP2), and carbonate d18O from Crawford
Lake. The abbreviations indicate the corresponding periods: OD1, Oldest Dryas; OD2, Older Dryas; IACP, Intra-Allerød
cold period; YD, Younger Dryas; PBO, Pre-Boreal oscillation; B, Bølling; A, Allerød. The arrows beside the dDBA curve
indicate the freshwater outburst from proglacial lakes. Calibrated ages from accelerator mass spectrometry radiocarbon
(AMS 14C) dating with errors are shown.
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[Webb et al., 2003]. The observed temperature decline in the
Chironomidae records was 5 to 6°C [Cwynar and Spear,
2001]; pollen data show 8°C increase in January temperatures and 4°C increase in July temperatures after the YD
[Huang et al., 2002; Webb et al., 2003]. The Blood Pond
pollen data were used to infer a 3°C decline in the mean
temperature of precipitation at the beginning of the YD, and
an 8°C increase at the end of YD (Figure 3).
3.2.3. Early Holocene (11.6 –8 ka)
[11] A series of abrupt temperature excursions is evident
in the early Holocene interval of the record. A temperature
decrease of 3°C follows a warming trend at the end of the
YD (just before 11.5 ka). This cooling may represent the
Preboreal Oscillation (PBO). After 11.5 ka, temperature
increased 6°C in 400 years, which is also observed in
the d 18O record from Crawford Lake [Yu and Eicher, 1998],
but was not seen in pollen-based climate reconstructions
from northeastern North America and in the Greenland ice
core records (Figure 3). In addition to PBO, some other
potential cold periods are also revealed by the lower dDBA
record, around on 10.9, 10.6, 10.3 to 10.1, 9.7, 9.3 and
8.9 ka.
3.3. Comparison of Pollen and Isotope-Based
Temperature Reconstructions
[12] Mean temperature of annual precipitation inferred
from pollen assemblages in the same sediment core using
the modern analog method [Webb et al., 2003] show similar
variations as inferred from the dDBA especially for the YD
(Figure 3, note the absolute values of pollen and dD inferred
temperatures differ due to independent calibrations). However, there are discrepancies between pollen and dDBA
inferred temperatures. For example, between 15 and
13.5 ka, pollen data suggest lower temperature than inferred
by dDBA record. Despite similar sampling resolution, multiple fluctuations of dDBA during the early Holocene are not
observed in the pollen data (Figure 3). The discrepancies
may result from misrepresentation of dry conditions as cool
conditions by the pollen method, and/or the misrepresentation of dry conditions as warm conditions by the isotopic
data (both dDBA from Blood Pond and carbonate d18O from
Crawford Lake). Although the northeastern North America
is known for positive P-E ratio, which favors relatively
small evaporative enrichment, a radical decrease in the P-E
balance could enrich D/H ratios of lake water. The low lake
level between 15 to 13.5 ka [Shuman et al., 2001] may have
enriched lake water D/H ratios, causing higher dDBA values.
Alternatively, the close proximity to the Laurentide ice sheet
during the pre-YD period could alter the moisture source for
precipitation, the precipitation seasonality. Local hydrologic
factors could alter the residence time of the lake, the balance
of groundwater and surface runoff into the lake, and/or the
source of groundwater. More studies are needed to reconcile
these discrepancies.
3.4. Overall Patterns of the Abrupt Climate Change
in Northeastern North America
[13] Comparison of the Blood Pond dDBA data with the
GISP2 d18O record reveals similarity in the number and
timing of abrupt climate events during the late Pleistocene
(Figure 3). Five Greenland cold regimes have been centered
around 14.8 (OD1), 14 (OD2), 13.2 (IACP), 12.3 (YD,
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12.9– 11.6) and 11.4 ka (PBO). Consistent with this, five
cold periods are found in Blood Pond. The d18O data from
Crawford Lake, Ontario and White Lake, New Jersey also
suggest similar climate shifts [Yu and Eicher, 1998; Yu,
2006]. The similarity in the sequence of the climate events
implies that repeated reversals during the late Pleistocene in
the North Atlantic region is related to a common cause i.e.,
the changes in thermohaline circulation due to freshwater
outbursts [Clark et al., 2001].
[14] During the early Holocene, the linkage of the climate
regimes of Greenland and northeastern North America
appears to have weakened. There is more variability in
the northeastern North America than in the Greenland, and
the amplitude of the temperature increase after the PBO is
larger in the northeastern North America records (6°C)
than in Greenland (2°C). The GISP2 d18O data show a
more gradual temperature increase until 10 ka (Figure 3).
Melting of the Laurentide ice sheet (LIS) from 12 to 10 ka
accelerated due to the elevated summer insolation in North
Hemisphere [COHMAP Members, 1988]. The combination
of the high insolation and rapidly retreating LIS may have
resulted in a faster warming trend on the North American
continent than in Greenland after the YD. Additionally,
Blood Pond dDBA values show six negative isotopic shifts,
indicating cold events lasting decades to centuries which are
not observed in the Greenland record (Figure 3). The timing
of these events is close to the freshwater outbursts of
relatively smaller magnitudes from Lake Agassiz, centered
at 10.6, 10.4, 10.3, 10.0, 9.5, and 9.2 ka [e.g., Clark et al.,
2001; Teller et al., 2002]. The cold freshwater may influence northeastern North America by cooling coastal waters
and the local atmosphere, rather than strongly affecting the
thermohaline circulation and altering the climate around the
North Atlantic basin, as has been suggested for the YD,
PBO and 8.2 ka events [e.g., Clark et al., 2001; Alley
and Agustsdottir, 2005]. Therefore, the effect of these
smaller freshwater outbursts on the Greenland ice sheet
was minimal.
4. Conclusions
[15] D/H ratios of behenic acid (C22 n-acid) or dDBA are
strongly correlated to the surface air temperature (T) along a
19-lake transect in eastern North America. The temperature
dependence of dDBA is 4.3%/°C. This is consistent with the
relationship between isotopic precipitation and T in eastern
North America (5.2%/°C), when the isotopic fractionation
of behenic acid (a = 0.8681) is taken into consideration. In
Blood Pond, isotope-inferred temperatures closely track
pollen-inferred temperatures. Therefore, the general features
of the dDBA are robust, although some disagreement between pollen and isotopic values demonstrates the potential
for different responses of lake water dD values and terrestrial vegetation to climate change. Abrupt climate events
observed in the GISP2 ice core during the Late Pleistocene
are also detected in dDBA record from Blood Pond. This
implies that climate change in both Greenland and northeastern North America during this time was related to a
common cause, namely the changes in thermohaline circulation in North Atlantic Ocean due to freshwater outbursts.
During the early Holocene, climate in northeastern North
America showed greater variability than in Greenland,
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HOU ET AL.: BLOOD POND, YD
possibly reflecting multiple climate forcing factors in northeastern North America versus a more uniform control by
solar insolation above Greenland ice sheet. Multiple episodes of fresh water outbursts from Lake Agassiz may have
induced a number of abrupt climate cooling events in
northeastern North America during the early Holocene,
each lasting several decades.
[16] Acknowledgments. We thank two anonymous reviewers for
their helpful comments on the early version of this paper. This work was
supported by grants from the National Science Foundation (NSF 0318050,
0318123, 0402383) to Y. Huang.
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D. R. Foster and W. W. Oswald, Harvard Forest, Harvard University,
Petersham, MA 03166, USA.
J. Hou and Y. Huang, Department of Geological Sciences, Brown
University, 324 Brook Street, Providence, RI 02912, USA. (yongsong_
[email protected])
B. Shuman, Department of Geography, University of Minnesota, 414
Social Science Building, Minneapolis, MN 55455, USA.
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